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When was the Montreal Protocol adopted and when did it enter into force?
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Ozone depletion
The Antarctic ozone hole reaches its maximum extent in October of each year. On October 7, 2021, when this image was captured, the Antarctic ozone hole spanned 24.8 million square km (9.6 million square miles).
The Montreal Protocol was adopted on September 16, 1987, and it entered into force on January 1, 1989.1
This international treaty was established to regulate the production and consumption of chemicals, such as chlorofluorocarbons and halons, that contribute to the depletion of the ozone layer.1